The 16-year-old half brother of Terry Smith has been arrested on suspicion of murder in Menifee, Calif., city Police Chief John Hill said Wednesday afternoon.

The body of Terry Smith, an 11-year-old boy who went missing from his Southern California home Saturday, was found in a shallow grave on the family’s property, Hill said. The body has yet to be positively identified but matches the description of the boy, KSDK reports.

Police say the teenager was the last one to see Smith alive. "The brother was walking away from their residence, turns back, sees that Terry's following him and tells Terry, 'Hey, go home,'" Deputy Albert Martinez told The Desert Sun this week.

The half brother, who shares the same mother as Terry, cooperated with police throughout the four-day search, the deputy told the Desert Sun.

Police discovered the body early Wednesday after receiving a tip. At the scene, police officers “located a shallow grave containing partially exposed human remains,” according to a statement. News reports show officers concentrating on a small hole near a tree about 75 feet from the house, the Associated Press reports.

The boy’s father, Terry Smith Sr., told NBC4 from his home in West Virginia that he suspected the 16-year-old had anger issues. "It didn't come as a surprise with his past," he said.

Smith adds that Terry did not have autism, despite earlier reports describing him as such. “Nope, nope, nope," Terry Smith, Sr. said. "In fact, when everyone in West Virginia heard that, they all flipped because they know better. He was a hyper little boy, he might have had ADHD.”

Thousands of volunteers took part in the search for Terry, setting up a command post and a Facebook page to share information about the missing boy, described as 4 feet 8 inches tall and weighing 76 pounds.

Adding to the challenges surrounding the search, temperatures in the area reached above 100 degrees each day. More than 1,000 law enforcement officers were involved in the effort to locate the missing boy.

"Our family would like to ask for the public and the media to allow us to grieve in peace," the statement said. "This has been a devastating week for our family and for everybody involved in the search. We are not prepared to provide an interview at this present time. Allow us to heal and pull ourselves together. This community has been amazing and we appreciate all the support. Our family can't thank each of you enough."